An important class of the chromane compounds are vitamin E and its esters. Due to the high relevance of this substance class in food and feed industry, new synthetic pathways of tocopherols and tocotrienols are of high interest.
J. Am. Chem. Soc. 2000, 122, 11553-11554 discloses that the gold(III) salt AuCl3 catalysis an intramolecular ring closure reaction of ω-alkynylfuran.
A. S. K. Hashmi et al., Adv. Synth. Catal. 2006, 348, 709-713 disclosed the first intermolecular reaction of an alkyne with furan using binuclear gold(l) complexes. However, said reaction formed next to a substituted phenol an almost equimolar amount of an alkenylfuran as side product.
N. Huguet et al. disclosed in Chem. Eur. J. 2013, 19, 6581-6585 an intermolecular gold(I) catalysed cyclization of furans with alkynes. Next to aromatic substituted alkynes such as phenylacetylene only very short chain alkyl acetylenes have been used.
Y. Román-Leshkov et al., Nature 2007, 447, 982-985, discloses that 2,5-dimethylfuran can be obtained from biomass.